Inflammation in the urinary tract or urethra of a patient which is usually, though not necessarily, due to bacterial infection is a condition requiring diagnostic accuracy by healthcare professionals. This is particularly critical for the diagnosis of sexually transmitted infections.
Sexually transmitted infections (STIs) are a major global cause of acute illness, infertility, long-term disability and death. Over the past decade, there has been a substantial increase in diagnoses of most sexually transmitted diseases in the UK. Overall, the increase between 1998 and 2008 has been approximately 60% with uncomplicated Chlamydia showing an increase of approximately 150% over the same period. The UK Government has responded by investing money in Genito-Urinary Medicine clinics and in public education. Increasing public awareness of the problems leads to an increase in the numbers of people wanting to be tested. The situation is very similar in the USA where approximately 19 million new STIs have occurred each year with almost half of them among young people of 15 to 24 years of age. Many infections can be treated and cured relatively easily and inexpensively if diagnosed sufficiently early. If, however, an infection is left untreated, many serious complications can occur. STIs can be passed from mother to baby before, during, or immediately after, birth. Such an infection has the potential to disable or kill the baby. Individuals, not aware that they are infected, innocently pass the infection on to their sex partners. Periodic, or even frequent, testing or screening of individuals is, for obvious reasons, recommended for individuals who change their sex partners.
Diagnosis of urethritis is conventionally carried out by light microscopical identification of Gram-stained urethral smears or by testing for leucocyte esterase (LE) in urine using dipsticks. Typically, an urethral smear is obtained using a swab or microbiological loop. Inflammation of the urethra is associated with an accumulation of polymorphonuclear leucocytes (also known as neutrophils) on its inner surface usually in response to the presence of bacteria associated with STIs. Microscopy has the merit of allowing a diagnosis to be made relatively quickly, for instance in less than 30 minutes, and therefore enables treatment of the patient at the first visit to a clinic, rather than having to wait for the results of laboratory tests for the causative agents to be made available. Although microscopical testing can be quick, this relies on the production of a urethral smear, an uncomfortable, invasive procedure which may deter men, in particular, from seeking diagnosis.
One alternative to urethral smears is a test developed over 20 years ago which determines the number of leucocytes in urine by measuring the concentration of the enzyme leucocyte esterase (LE) using dipstick tests. The LE test is attractive as a screening tool since it is inexpensive, non-invasive and easy to use in an outpatient setting. However, while it is capable of identifying a large proportion of Chlamydia urethral infections, it misses many other infections.
WO 98/11259 describes the testing of genitourinary body fluid samples using a nucleic acid amplification technique (NAAT) to detect a plurality of sexually transmitted disease pathogens including Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium and Ureaplasma urealyticum. Examples of genitourinary body fluid samples that are suitable for use in the test procedure according to WO 98/11259 include first pass urine. It is noted here that first pass urine is usually the easiest sample to obtain from a patient.
It is, however, thought that testing techniques based on nucleic acid amplification are not able to identify infections in all tested patients who are actually infected. In cases where an infected male is wrongly tested negative, a female partner may be at increased risk of Chlamydia trachomatis infection.
An aim of the present invention is to solve the problems of the prior art procedures by providing a quick, point-of-care testing procedure which is more sensitive and more selective than prior art procedures which can be carried out on a urine sample provided by a patient.